Three-dimensional (3D) shape reconstructions and metrology measurements are often limited by depth-of-field constraints. Current focus-detection-based techniques are insufficient to profile out-of-focus 3D objects with high axial accuracy. Extended-focus imaging (EFI) techniques can improve the range and precision of such measurements. By incorporating digital refocusing with multiwavelength interferometry, a holographic imaging solution is presented in this paper to accurately measure 3D objects over a large depth range. Accuracy and repeatability of the proposed EFI technique are validated by digital simulations and refocusing experiments. A reconstruction example demonstrates the feasibility of high-precision 3D measurements of objects deeper than the system’s classical depth of field.
© 2012 Optical Society of America
Original Manuscript: September 23, 2011
Revised Manuscript: December 14, 2011
Manuscript Accepted: December 15, 2011
Published: May 18, 2012
Li Xu, Carl C. Aleksoff, and Jun Ni, "High-precision three-dimensional shape reconstruction via digital refocusing in multi-wavelength digital holography," Appl. Opt. 51, 2958-2967 (2012)